Recently, in automobiles, as higher accuracy and higher functionality of vehicle control by an electronic control unit (ECU), in order to acquire various types of vehicle information (including peripheral information of vehicle) and control various parts of the vehicle, a large number of sensors or actuators are provided, and the number of communication lines between the sensors or the actuators and the ECU increases significantly. An application of the power line communication apparatus using the power line of the DC power source as the communication lines is disclosed in PTL 1. In PTL 1, a communication phase and a power supply phase are provided for the use of the power line and the power line is used for any one of communication and power supplying for each phase.